Numerous efforts have been made to create various types of surgical methods and implants that can repair or replace damaged or diseased cartilage segments, in mammalian joints such as knees, hips, and shoulders. Those efforts generally can be divided into two categories: (1) non-resorbable implants, designed to remain in a repaired joint for the entire remaining life of the patient; and (2) resorbable implants, made of materials that will gradually dissolve and be replaced by natural biological materials.
It also should be noted that most types of resorbable implants are designed for regeneration of cartilage by living cells, rather than for replacing cartilage by synthetic polymers or other non-living materials. Cartilage regeneration efforts using resorbable implants usually involve transplantation of chondrocyte and/or mesenchymal cells, and the resorbable implants are designed to shelter and nurture the transplanted cells, allowing them to be “seeded” into the resorbable implant a week or so prior to implantation, thereby giving the cells a “headstart” before they are transplanted into the damaged joint.
At the current time, the devices discussed herein fall into the category of non-resorbable implants, made of synthetic materials and designed to remain in a joint for the remaining life of the patient. These implants will be used to replace, rather than regenerate, a cartilage segment that has become damaged or diseased. Accordingly, this current invention, as described and claimed below, is limited to non-resorbable implants, designed for replacement rather than regeneration of damaged cartilage.
Nevertheless, it should be recognized that, as research on these devices progresses, it may also be possible to adapt these devices for use in: (i) implants that use resorbable materials; and/or, (ii) cell-transplanting operations, designed to promote the regeneration of cartilage by transplanted cells. Accordingly, this current invention is not intended to close off and deny those possibilities; instead, this invention is intended as a focused and targeted step forward in the development of a highly useful class of non-resorbable implants, with the understanding that this technical development might also be extendible, in the future, to a different and distinct approach to cartilage repair.
In a similar manner, at the current time, any references herein to “implant”, “device”, or similar terms are limited to devices that will be implanted surgically, into a mammalian joint, to repair or replace a segment of hyaline cartilage. As known to those skilled in the art, hyaline cartilage is the term used to describe the type of cartilage that covers the condyles (rounded ends) of articulating bone surfaces, in joints such as knees, hips, shoulders, fingers, wrists, etc.
Two other types of cartilage (known as elastic cartilage, and fibrocartilage) also exist in mammals, and are present in the ears, nose, windpipe, etc. If desired, the invention disclosed herein can be adapted for use in repairing elastic cartilage and/or fibrocartilage. However, it should be recognized that, because of the compressive and shear forces involved, replacing damaged hyaline cartilage in load-bearing joints (especially the knees, hips, and shoulders) is much more difficult than replacing cartilage in the ears, nose, or other locations in the body. Accordingly, the only prior art which is regarded as relevant herein involves efforts to repair damaged hyaline cartilage knees, hips, shoulders, or ankles. Any other type of cartilage repair (including repair of damaged cartilage in finger joints) will not have to meet or satisfy the types of mechanical stresses that will be placed on cartilage segments in joints such as the knees, hips, or shoulders.
A major goal of this invention is to provide non-resorbable devices that can be inserted into a damaged or diseased joint using “minimally invasive” methods and tools, which includes arthroscopic methods and tools. However, it should be recognized that some of the devices disclosed herein may be able to provide improved implants that can be implanted using older “classical” or “open joint” surgical methods. In addition, it should be recognized that there is not always a clear dividing line between classical surgical methods (often referred to as “open joint” methods) and “minimally invasive” methods, since any competent surgeon will always minimize the amount of cutting and other damage and disruption to muscles, ligaments, blood vessels, and other tissues, in any surgical operation, in view of the needs of the operation and the patient.
Accordingly, any use herein of broad terms such as “surgery” or “surgical” are deemed to include arthroscopic and other minimally invasive methods; and, whenever use is made of a narrow term such as “arthroscopic”, it should be realized that arthroscopic use is the primary goal of this invention, but the devices disclosed herein may also be adapted for use with other (classical, open joint) surgical methods.
Background information on non-resorbable implants in the prior art is contained in various medical textbooks, such as Campbell's Operative Orthopedics, and in numerous articles and patents, such as U.S. Pat. No. 6,132,468 (by the same inventor herein) and other patents and articles cited therein.
The Applicant herein, an orthopedic surgeon who specializes in repairing joints such as injured or diseased knees, has submitted a number of patents and pending patent applications which disclose several of the components of the assembled multi-component device disclosed herein. Those patents and patent applications include:
U.S. Pat. No. 6,132,468 (issued Oct. 17, 2000), which discloses (i) flexible inflatable envelopes, which can be inserted into a joint in collapsed fashion, via an arthroscopic insertion tube, and then filled with a polymer that will harden and set to form a complete implant; and, (ii) tools and templates that can be used to remove cartilage and prepare a hard bone surface, arthroscopically;
Application No. 60/192,482 and Ser. No. 09/818,811, both of which describe hydrogel components that can be reinforced by a three-dimensional woven matrix, of a type that was originally developed for entirely different materials such as used in aerospace applications;
Application No. 60/250,091, entitled “Multi-Perforated Non-Planar Device for Anchoring Cartilage Implants and High-Gradient Interfaces,” which discloses a “perforated waffle” type of interfacing layer, for reinforcing and strengthening the attachment between a soft cushioning material (such as a gel) and a substantially harder surface, such as a plastic shell or bone surface.
Application Ser. No. 09/393,522, entitled “Improved Resorbable Scaffolds to Promote Cartilage Regeneration,” which discloses a scaffolding structure with a rim-and-runner system comparable in various respects to the anchoring component described below.
Application Ser. No. 09/659,321, entitled “Rim Components for Use in Arthroscopic Replacement of Cartilage Using Inflatable Envelopes,” which discloses flexible ring-type structures that can be inserted into a joint arthroscopically, anchored to a prepared bone surface using pins or similar devices, and then used to help position, grip, and firmly secure an envelope-type device which can also be inserted arthroscopically.
Application Ser. No. 09/690,897, entitled “Tool Set to Assist Arthroscopic Replacement of Cartilage Using Flexible Inflatable Envelopes,” which discusses arthroscopic tools and tool guides that can be used to remove cartilage and prepare a hard bone surface which will be ready to receive a mass-manufactured implant.
Application Ser. No. 09/690,897, entitled “Semi-Permeable Membranes to Assist in Cartilage Repair,” describes implants which are covered by semi-permeable membranes that will allow water to permeate through them readily, but which will not allow larger molecules that cause synovial fluid to be very slippery (including hyaluronic acid, lubricin, and surface-active phospholipids) to penetrate through them easily.
The teachings of the above-listed patents and patent applications are incorporated herein by reference, as though fully set forth herein. Any applications listed above which have not been issued or otherwise published by the date of issuance of any patent issuing from this current application will be laid open for public inspection and copying on that date.
In his ongoing efforts to develop improved implants for repairing or replacing cartilage, the Applicant herein has realized that a particular combination of components, arranged in a particular manner as disclosed below, can provide an improved device with a combination of highly useful traits and advantages. Such devices can be implanted entirely through arthroscopic or minimally-invasive incisions, to minimize damage and disruption to surrounding tissues and vasculature. After implantation, these devices can provide a combination of highly advantageous traits, on both the “anchoring” side (i.e., the side of an implant which presses against a supporting bone structure, such as a femoral or tibial condyle, in a knee) and the “articulating” side (i.e., the side which is exposed to synovial fluid in a joint and which will slide and rub against another cartilage or implant surface in the joint).
Accordingly, one object of this invention is to disclose an improved non-resorbable implant for repairing or replacing damaged or diseased cartilage in a joint such as a knee, wrist, ankle, or finger, and possibly in a ball-and-socket joint such as a hip or shoulder.
Another object of this invention is to disclose an improved non-resorbable implant for repairing or replacing cartilage, having both (i) a relatively pliant and non-rigid “bearing surface” which emulates the articulating surface of a segment of natural cartilage, and (ii) an anchoring portion which is sufficiently flexible to allow it to be inserted into a joint, during surgery, through an arthroscopic insertion tube.
Another object of this invention is to disclose an improved non-resorbable implant for repairing or replacing cartilage, which is thin enough to allow it to be rolled up into a cylindrical shape that can be inserted into a joint through an arthroscopic insertion tube, and then unrolled, inside the joint, in a manner which allows it to be pinned or otherwise anchored to a prepared bone surface.
Another object of this invention is to disclose an improved non-resorbable implant for repairing or replacing cartilage, made of components that are small enough to be inserted into a joint via arthroscopic methods, and then assembled in situ, inside the joint, to form a complete and functional implant.
These and other objects of the invention will become more apparent through the following summary, drawings, and description of the preferred embodiments.